Abkhazia's foreign ministry said it has no information about the Georgian allegations and would not comment, but in the past it has denied Georgian allegations.
Russia maintains that it has secured its radioactive material — including bomb-grade uranium and plutonium — and that Georgia has exaggerated the risk because of political tension with Moscow. But while the vast majority of the former Soviet Union's nuclear arsenal and radioactive material has been secured, U.S. officials say that some material in the region remains loose.
"Without a doubt, we are aware and have been over the last several years that not all nuclear material is accounted for," says Simon Limage, deputy assistant secretary for non-proliferation programs at the U.S. State Department. "It is true that a portion that we are concerned about continues to be outside of regulatory control."
U.S. efforts to prevent smuggling have prioritized bomb-grade material because of the potential that a nuclear bomb could flatten a U.S. city. But security officials say an attack with a dirty bomb — explosives packed with radioactive material — would be easier for a terrorist to pull off. And terrorist groups, including al-Qaida, have sought the material to do so. A study by the National Defense University found that the economic impact from a dirty bomb attack of a sufficient scale on a city center could exceed that of the September 11, 2011, attacks on New York and Washington.
The U.S. government has been assisting about a dozen countries believed to be vulnerable to nuclear smuggling, including Georgia, to set up teams that combine intelligence with police undercover work. Limage says Georgia's team is a model for the other countries the U.S. is supporting.
On Jan. 6, police arrested a man in Georgia's capital, Tbilisi, and seized 36 vials with cesium-135, a radioactive isotope that is hard to use for a weapon. The man said he had obtained the material in Abkhazia. In April, Georgian authorities arrested a group of smugglers from Abkhazia bringing in three glass containers with about 2.2 pounds (1 kilogram) of yellowcake uranium, a lightly processed substance that can be enriched into bomb-grade material.
"At first we thought that this was coincidence," said Archil Pavlenishvili, chief investigator of Georgia's anti-smuggling team. "But since all of these cases were connected with Abkhazia, it suggests that the stuff was stolen recently from one particular place. But we have no idea where. "
Days later, more evidence turned up when Turkish media reported the arrest of three Turkish men with a radioactive substance in the capital, Ankara. Police seized 2.2 pounds (1 kilogram) of cesium-135, the same material seized in January in Tbilisi.
Georgian officials said the suspects were residents of Germany and driving a car with German plates, but that the material had come from Abkhazia. Turkish authorities said the men had entered Turkey from Georgia. Information provided by German authorities led to the arrest in June of five suspects in Georgia with 9 vials of cesium-135 that looked very similar to the vials seized in January.
The Batumi investigation started after the arrest of two men in the city of Kutaisi in February 2011 year with a small quantity of two radioactive materials stolen from an abandoned Soviet helicopter factory, according to Georgian officials. The men said that a businessman, Soslan Oniani, had encouraged them to sell the material.
Police interviewed Oniani and searched his house, but found insufficient evidence to arrest him, according to officials. Still, they kept monitoring him through phone taps and an informant. Georgian officials say Oniani was a braggart, who played on his relationship with his cousin, Tariel Oniani, a well- known organized crime boss convicted in Russia of kidnapping.
Early this year, Soslan Oniani started talking about a new deal. Through surveillance and phone taps, police learned of the meeting in Batumi and monitored it. While no money passed hands, the men discussed an illegal deal, which is sufficient for prosecution in Georgia.